Video stream display and protection method and device

ABSTRACT

The present invention relates to a process for the distribution of video streams to a plurality of addressees, comprising a marking stage consisting in adding at least one visual element to this video stream, which marking stage is applied to an original video stream common to all the addressees and which is personalized for each addressee by the addition of a visual elements specific to the addressee that allows a rapid visual identification of this addressee, characterized in that this added visual element replaces part of the original video stream that is stored in the complementary information on the multimedia server. Another characteristic of the invention is that the reconstitution and the display of the original stream are carried out on the client equipment from the modified stream and from complementary information sent by the server after authentication of the client and as a function of his rights for being read and viewed without the display of the visual elements.

The present invention relates to a process for the distribution of digital video streams, of which the problem is to prevent them from being illegally copied and/or distributed by the addition into these video streams of visual elements concerning each person receiving the original stream. The addition of these personalized visual elements should permit the immediate identification of the person for whom the original film is intended in such a manner that once taken out of its context of normal and authorized reading, the reading of this video stream allows the authentication of the origin of the fraud, e.g., in the case of pirating or of illicit distribution of copies of these audiovisual streams. The objective is to allow the source of the fraud to be traced if it took place, and especially to have a dissuasive effect on any ill-intentioned person.

Tattooing effects are known that permit the insertion into a video stream of visual elements that can not be detected by the human eye but can be recognized by a computer program, even after several manipulations of the video stream. These visual elements can also be personalized for one or several users. The disadvantage of the existing solutions is that they do not allow the detection of a fraudulent copy without employing complex techniques for the analysis of the video stream. The present invention permits the immediate identification without supplementary means of a fraudulent copy while leaving the video stream in plaintext [non-encrypted] during an authorized display.

The present invention is based on a client-server system with the objective of identifying the person who desires to display a video stream and to identify the reading device on which the display will be made. These identifications allow the user to first recover on his personal or another reading device (sent physically by CD-ROM or DVD, or downloaded to onto a computer or a decoder (set-top box)) a version of the video stream that he selected and adapted for his use. Before or during this transmission the server will perform the appropriate adaptation of the stream for this client. For example, if the client reserves a film in advance, the visual elements are introduced by the server and a modified stream is downloaded into the memory or onto the hard disk of the reading equipment of the client. If the client desires to view a film immediately, the server introduces the appropriate visual elements gradually and transmits the modified stream to the user in real time.

The original stream to which personalized visual elements were added will be called “modified stream” or “marked stream” in the following. At the moment of the reading of this modified stream that is stored on the client apparatus, a new client-server connection is necessary in order that during the viewing of this modified stream no visual element for the identification of the client appears on the viewing screen. On the other hand, if this modified stream has left the client apparatus (by means of a copy or a downloading) while its is being read onto another device that has no connection to the server, the visual elements are displayed.

The generation of the protected video stream is adapted to the user and carried out by the server. The latter analyses this original video stream in order to insert supplementary visual data that is superposed on the video stream or replaces the original content. The operation consists in analyzing this original video stream in order to designate the position (static or dynamic), the type and quantity of visual elements to be inserted as well as the number of insertions and their appearance time on the screen. One embodiment is that these visual elements never appear at the same location during the reading of the protected stream and that its content furnishes a maximum of information concerning the user authorized to see the film, such as his name, address, telephone numbers or any information that can identify him or rapidly authenticate him. All this information relative to the client will be called “authenticating information” in the following. The server makes an analysis of the stream and changes a certain amount of information in the original stream with visual elements of the same format or compatible with the original information. This original information is extracted from the stream, stored on the server and replaced by visual elements relative to the user. This operation is called “marking” and produces the modified stream. The original information stored on the server is called “complementary information”. Another variant is to superpose the visual elements on the original film.

The resulting modified stream is advantageously totally compatible with the norm or the standard with which the original stream was generated.

The restitution of the original video stream takes place on equipment compatible with the invention and that will make a connection to the server in order to recover the complementary information that it is saving in real time during the reading of the protected video stream and realize the restitution of the original stream. This operation is called “removal of the marking” [unmarking, demarking?]. Without the operation of the recovery of the complementary information in real time from the server only the stream marked with the visual elements is displayed and therefore all the information concerning the client is displayed storing the entire duration of viewing. Thus, a viewing of the original stream is only possible on the suitable client equipment and any other form of display will display this authenticating information. Any person in possession of a non-authorized copy of this modified video stream also has all the personal authenticating information for finding the client at the origin of this copy.

However, the presence of visible visual elements might tempt ill-intentioned persons to make them disappear. Since the visual elements were inserted in the video stream by replacing original parts, the ill-intentioned person might insert visible traces in order to hide the visual elements indicating the origin of the video stream. However, the information about positions of the visual elements in terms of a selection of modified frames, about the position in the frame selected, about the form and the size of the visual element inserted remain visible and can be found again by an adequate processing. Since the marking was made by the server, all the information relative to the position, form size of the mark and to the number of frames into which it was inserted are known to the server, that identifies each user in a unique manner in this way. The knowledge of this information is therefore sufficient to identify the ill-intentioned person who substituted the visual elements by visible traces.

The presence of visible visual objects might also tempt several users of the same distribution group, since they have access to the same film, to compare the differently marked video streams that they have and to make a new one from them of which all or part of the visual objects would have been removed by combining the non-modified parts or by replacing a picture containing a visual object by an original picture. In order to prevent this problem, the process in conformity with the present invention provides that the form, color, size of the visual objects and the number of frames in which the visual object is inserted are obtained for each user from a combinatory method relative to a group of users and that the visual object contains at least one visual part with an identical position for all the users of the group representing an identifier of this group of users.

The operations of marketing transmission, removal of the marking and a display can be made sequentially in real time during a single client-server connection.

In its most general meaning the invention relates to a process for the distribution of video streams to a plurality of addressees, comprising a marking stage consisting in adding at least one visual element to this video stream, which marking stage is applied to an original video stream common to all the addressees and which is personalized for each addressee by the addition of a visual elements specific to the addressee that allows a rapid visual identification of this addressee, characterized in that this added visual element replaces part of the original video stream that is stored in the complementary information on the multimedia server.

This visual element is advantageously generated in two stages, the first stage of which consists in processing the marking data with any format in such a manner as to generate marking objects describing the visual element to be displayed and the second stage of which consists in adding this visual element into said video stream.

The reconstitution of the original stream is advantageously carried out on the client equipment from the modified stream and from complementary information sent by the server after authentication of the client and as a function of his rights for being read and viewed without the display of the visual elements.

According to an embodiment this marking stage allows the inclusion in the video stream of all types of visual elements whose form, position and color are determined.

According to an embodiment this marking stage allows the inclusion in the video stream of all types of visual elements whose form, position and color are variable.

According to another embodiment the process comprises a control stage for authorizing one or several private copies. The complementary information is advantageously sent in real time.

According to an embodiment the position, form, color, size of the visual object inserted and the number of frames into which the visual object is inserted are unique and personalized for each user.

According to another embodiment the position, form, size of the visual objects inserted and the number of frames into which the visual object is inserted are obtained from a combinatory method relative to a group of users and the visual object contains at least one part with an identical position for all the users of the group representing an identifier of this group of users.

The invention also relates to a system for carrying out the process for the distribution of video streams that is constituted by a marking module comprising a module for generating visual elements personalized for each user, a module for inserting these visual elements into the original stream, thus producing a marked stream and complementary information stored in the server, and a module for removing the marking in which the reconstitution of the original stream is performed from the marked stream and the complementary information sent by the server.

The present invention will be better understood from a reading of the following non-limiting exemplary embodiments making reference to the attached drawing in which the figure describes the total architecture of the system for implementing the process in accordance with the invention.

A particular exemplary embodiment consists in distributing films coded in conformity with the MPEG-2 norm.

When a client 3 connects to server 2 for ordering a film A, he selects a film A in a list supplied by server 2 and relative to the content of film base 1. Once his selection and the order transaction have been validated by server 2, the latter transforms film A selected in base 1 into a film B that contains, in visual form and included in the video stream, the personal information 24 of the client. This personal information of the client is constituted during his membership to the service and, especially during a connection J, and stored in a database of personal information 24 at the level of server 2.

A digital video stream of the MPEG-2 type is constituted by sequence of pictures (or planes or frames) regrouped in groups of pictures (GOP's). A picture can be of the I type (Intra), P type (predicted) or B (bidirectional). The I pictures are the reference pictures. They are entirely coded and are therefore of an elevated size and do not contain information about the movement. The I pictures are constituted by slices that themselves contain macroblocks and blocks.

The transformation is performed by module 21 and consists in this non-limiting example in changing a slice of an I picture and all the ten I pictures. The position of the slice is selected randomly in the picture and this slice is replaced by a slice created in such a manner as to be inserted perfectly into binary stream A while respecting the size of the picture and the composition of the macroblocks. This slice substitution operation is rendered visually by the appearance of a black band containing a text in white characters and giving the “last name, first name, address, telephone No.” of the client determined from the personal data D stored in the personal information base 24 of server 2. Complementary information C, that is, the content and the position in the picture of each slice removed as well as the number of the picture concerned are stored in buffer 23 of server 2.

Module 22 permits modified stream B to be prepared for its transport to client 3 by transport means 4. For example, film B is recorded on a physical support such as, e.g., a disk and sent by mail to the client 3. Upon receiving this disk, user 3 can read it in his disk reader 31 because the stream received is totally compatible with the MPEG-2 norm.

Either disk reader 31 of the client 3 has module 311 necessary for the client-server connection 5, in which case during the reading of this disk this module 311 included in disk reader 31 will recover via telecommunication network 5 the complementary information C contained in buffer 23 in order to compose, prior to the display on viewing screen 6, a stream I identical to original stream A, that is, without the presence of authenticating information. Stream I is then decoded in a classic manner by module 312 of module 31, which module 312 is a standard video MPEG-2 reader. At the output of this module 312 the display is made on viewing screen 6.

Or, if DVD reader 31 of client 3 is not equipped with this system 311 or if it does not succeed in identifying itself correctly via connection 5, in this case the white-on-black text band appears [on] all 10 I pictures on screen 6 since stream I had not been transformed by module 311.

Every private copy of the disk will be viewable without authenticating information in the same manner as the original disk on any module authorized to display it as a function of the client rights.

If copies are made by the client for a fraudulent use (e.g., for resale or distribution) the authenticating information can be read by a person who sees it on his reader and any person finding such an illicit copy can go back to the source of the copy with the aid of the personal information contained in these text bands.

Another exemplary embodiment is constituted by the fact that the visual elements are no longer authenticating information but rather modified slices containing text or parts of any picture. For example, only a first user authorized to view the film can view it after the removal of marking performed by module 311. In the case in which the film is copied in a fraudulent manner by a second user who is not authorized, the second user sees the film with the visual elements displayed and therefore the visual quality of the film is degraded. Every user authorized to view the film can view it on any device 31 by means of its parameters for identifying it to the server necessary for authorizing the connection via network 5. 

1-10. (canceled)
 11. A process for distributing video streams to a plurality of addressees, comprising a marking step comprising adding at least one visual element to a video stream, which marking step is applied to an original video stream common to all of the addressees and which is personalized for each addressee by addition of a visual element specific to the addressee that allows rapid visual identification of the addressee, wherein the added visual element replaces part of the original video stream that is stored in complementary information on a multimedia server.
 12. The process according to claim 11, wherein the visual element is generated in two steps, a first step comprising processing marking data with any format in such a manner as to generate marking objects describing the visual element to be displayed and a second step comprising adding the visual element into the video stream.
 13. The process according to claim 11, further comprising reconstitution of the original stream on client equipment from the modifies stream and from complementary information sent by the server after authentication of a client and as a function of client rights for being read and viewed without display of the visual elements.
 14. The process according to claim 11, wherein the marking step allows for inclusion in the video stream of visual elements whose form, position and color are determined.
 15. The process according to claim 11, wherein the marking step allows for inclusion in the video stream of visual elements whose form, position and color are variable.
 16. The process according to claim 11, further comprising a control stage for authorizing one or several private copies.
 17. The process according to claim 11, wherein the complementary information is sent in real time.
 18. The process according to claim 11, wherein the position, form, color, size of the visual object inserted and the number of frames into which the visual object is inserted are unique and personalized for each user.
 19. The process according to claim 11, wherein the position, form, size of the visual objects inserted and the number of frames into which the visual object is inserted are obtained from a combinatory method relative to a group of users and the visual object contains at least one part with an identical position for all users of a group representing an identifier of the group of users.
 20. A system for distributing video streams in accordance with claim 11, comprising a marking module comprising a module for generating visual elements personalized for each user, a module for inserting visual elements into the original stream, thereby producing a marked stream and complementary information stored in the server, and a module for removing the marking in which reconstitution of the original stream is performed from the marked stream and the complementary information sent by the server. 